In sub-Saharan Africa women are more likely than men to be infected with HIV, while in other regions of the world men are more likely than women to be infected. At the global level, half of adults living with HIV are women. However, in sub-Saharan African countries with the highest HIV prevalence, women represent the majority of people living with HIV/AIDS (UNAIDS, 2010; 2011b). Levels of new infections in sub-Saharan Africa continue to remain higher among women than men, particularly in the younger groups (UNAIDS, 2010). In this region, the adult mortality rate due to AIDS is also higher for women than for men. In other regions, men are more likely to be infected with HIV than women, often in concentrated epidemics involving men who have sex with men or people who inject drugs, and adult men have a higher risk of mortality due to AIDS than adult women (UNAIDS, 2010).

Women face a higher risk of becoming infected with HIV during unprotected sexual intercourse than men. In addition to being more biologically vulnerable than men to infection, women and girls may have difficulties in negotiating condom use with their partners. In particular, sexual violence and abuse hampers women’s ability to protect themselves from HIV infection and/or to assert healthy sexual decision making. Furthermore, sex outside of a marital union and multiple sexual partnerships are often tolerated for men (though not for women) and hence a woman can be vulnerable to HIV infection because of her husband’s concurrent sexual relations. These risks are higher in contexts where women have much older partners than themselves, have a lower status than men and are economically dependent on men due to social or legal discrimination. (United Nations, 2000; 2011a; WHO, 2009; UNAIDS, 2010)

Young women and young men may have different HIV-related knowledge and behaviour. In many countries, HIV-related knowledge is still lower among young women than among young men (UNICEF, 2011; United Nations, 2011c). In general, the knowledge of HIV prevention among young people has increased but remains low in many developing countries (United Nations, 2011c).

More girls than boys start their sexual life early, although the prevalence of early sex is declining for girls as well as for boys (United Nations, 2011a; UNICEF, 2011). In countries with high HIV prevalence, young women are at particularly high risk of HIV infection when they have older male sexual partners who are more likely than younger men to be infected with HIV (WHO, 2009).

Young men are more likely than young women to report having multiple sex partners, however, compared to women, young men are also more likely to report using condom during sex with a non-marital, non-cohabiting partner (defined as higher-risk sex) (UNICEF, 2011). In some countries, the proportion of women reporting multiple sex partners and not using condom has increased (UNAIDS, 2010).

HIV/AIDS has placed significant burdens on family members, especially women (United Nations, 2008). The primary caregivers for sick patients are usually women and girls within a family. HIV/AIDS has also led to a large number of orphans, who are taken care of by other family members or institutions. In Africa, for example, it is often grandmothers who take responsibility for this care, in skipped generation households.

Multiple sexual partnerships and condom use at last high-risk sex (i.e. sex with a non-marital, non-cohabiting partner) by sex and age

Comprehensive correct knowledge of HIV/AIDS by sex and age

Other data can contribute to the understanding of the causes and consequences of HIV/AIDS. Such data may refer to: violence against women; early sex; or time use for caring for household members who are living with HIV.

Additional data on sexual behaviour and HIV prevention, prevalence and treatment related to special risk groups such as sex workers, men who have sex with men, and people who inject drugs should also be considered.

Sentinel surveillance may collect data on HIV status and sexual behaviour for populations with high risk behaviours such as sex workers, injecting drug users and men who have sex with men.

Population-based surveys with HIV testing such as Demographic and Health Surveys and AIDS Indicators Surveys provide data on HIV prevalence. These surveys as well as MICS and reproductive health surveys also provide other HIV-related data, such as: knowledge of HIV transmission and prevention, multiple sex partners, use of condom during sexual intercourse with a non-marital, non-cohabiting sexual partner in the last 12 months, and access to antiretroviral therapy.

Integrated Biological and Behavioural Surveillance (IBBS) Surveys can provide data on key populations at higher risk of HIV infection, such as men who have sex with men, sex workers, and people who inject drugs.

Reports from health facilities, including antenatal clinics attended by pregnant women, may provide information on results from HIV-tested blood from sample of patients, and information on access to antiretroviral therapy.

Time use surveys can provide data on time spent caring for household members who are sick or disabled, including household members who are HIV infected. However, data specific to care given to HIV infected persons are difficult to obtain.

Non-participation in HIV-testing in population-based surveys is often higher for men than for women (Mishra and others, 2008), which may induce a sex bias in estimates of HIV prevalence.

Normative reporting (interviewed persons giving answers perceived to be socially desirable) may artificially increase or decrease the estimated gender gap in sex-related behaviour such as condom use at last high-risk sex and multiple sex partners.